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Abstract:

An exemplary lens module with focusing function includes a lens group, a
lead screw, a transmission member, an actuator, and two stop portions.
The lens group is slidable along the optical axis thereof. The lead screw
is set so that the longitudinal direction thereof is essentially parallel
to the optical axis. The transmission member is secured to the lens
group, and includes a deformable screw-engaging portion. The deformable
screw-engaging portion is disengageably engaged with the lead screw. The
actuator is configured for driving the lead screw to rotate to force the
transmission member to move along the lead screw. The two stop portions
are configured for delimiting a movable boundary of the transmission
member along the lead screw. The surrounding portion will disengage from
the lead screw when the surrounding portion abuts against the stop
portion and the lead screw continues rotating.

Claims:

1. A lens module with focusing function comprising:a lens group being
slidable along the optical axis thereof;a lead screw set in such a manner
that the longitudinal axis thereof is parallel to the optical axis;a
transmission member secured to the lens group, the transmission member
comprising a deformable surrounding portion partially surrounding and
engaging with the lead screw, the surrounding portion being engaged with
the lead screw;an actuator for driving the lead screw to rotate to force
the transmission member together with the lens group to move along the
lead screw; andtwo stop portions for delimiting a movable boundary of the
transmission member along the lead screw, the surrounding portion being
deformable to disengage from the lead screw in the case that the
surrounding portion abuts against one of the stop portions and the lead
screw continues rotating.

2. The lens module as claimed in the claim 1, wherein the lens group
comprises a holder secured to the transmission member and at least one
pickup lens held by the holder.

3. The lens module as claimed in the claim 1, wherein the surrounding
portion is engaged with the lead screw using multiple threads.

4. The lens module as claimed in the claim 1, wherein the thread angle of
the lead screw is in an approximate range of 45.degree.˜60.degree..

5. The lens module as claimed in the claim 1, wherein the thread angle of
the lead screw is about 55.degree..

6. The lens module as claimed in the claim 1, wherein the surrounding
portion surrounds more than 120.degree. of the circumference of the lead
screw.

7. The lens module as claimed in the claim 1, wherein the surrounding
portion is made of material selected from a group consisting of resilient
plastic and resilient metal.

8. The lens module as claimed in the claim 1, wherein the surrounding
portion is made of material selected from a group of ployoxymethylene and
elastic steel.

9. The lens module as claimed in the claim 1, wherein the actuator is
selected from a group of servomotor and step motor.

10. The lens module as claimed in the claim 1, further comprising a lens
barrel for receiving the lens group, the lead screw, the transmission
member, the actuator, and the two stop portions, a slidable member and a
guide, wherein the slidable member is secured to the lens group, the
guide is fixed with respect to the lens barrel configured for guiding the
slidable member and the lens group sliding along the optical axis.

11. The lens module as claimed in the claim 10, wherein the slidable
member defines a through hole therein, the guide is a guiding rod, the
guiding rod being set parallel to the optical axis and matingly inserting
through the through hole, the slidable member being slidable along the
guiding rod.

12. The lens module as claimed in the claim 1, wherein the stop portions
are nuts fixed to the lead screw.

13. The lens module as claimed in the claim 10, wherein the lens barrel
defines a guiding groove in the inner surface thereof, the guiding groove
extending in a direction essentially parallel to the optical axis, the
slidable member being fittingly and slidably inserted in the guiding
groove.

14. The lens module as claimed in the claim 10, wherein the lens barrel
defines a concave space, the lead screw being rotatably received in the
concave space, two bounding surfaces of the concave space acting as the
two stop portions, the two bounding surfaces of the concave space facing
each other and being essentially perpendicular to the lead screw.

15. A lens module with focusing function comprising:a lens group being
slidable along the optical axis thereof;a lead screw set in such a manner
that the longitudinal direction thereof is parallel to the optical axis;a
transmission member secured to the lens group, the transmission member
comprising a deformable screw-engaging portion disengageably engaged with
the lead screw;an actuator for driving the lead screw to rotate to force
the transmission member to move along the lead screw; andtwo stop
portions for delimiting a movable boundary of the transmission member
along the lead screw, the screw-engaging portion being disengaged from
the lead screw in the case that the surrounding portion abuts against one
of the stop portions and the lead screw continues rotating.

16. The lens module as claimed in the claim 15, wherein the screw-engaging
portion discontinuously surrounds the lead screw.

17. The lens module as claimed in the claim 16, wherein the screw-engaging
portion is made of resilient material select from a group of
ployoxymethylene and elastic steel.

18. The lens module as claimed in the claim 15, further comprising a lens
barrel for receiving the lens group, the lead screw, the transmission
member, the actuator, and the two stop portions, a slidable member and a
guide, the slidable member being secured to the lens group, the guide is
fixed with respect to the lens barrel configured for guiding the slidable
member and the lens group sliding along the optical axis.

19. A lens module with focusing function comprising:a lens group;a lead
screw set in such a manner that a longitudinal direction of the lead
screw is essentially parallel to the optical axis of the lens group;a
transmission nut defining a longitudinal gap therein to cause the nut
discontinuous in the circumferential direction thereof, the transmission
nut being meshed with the lead screw except the gap, and fixed with
respect to the lens group;an actuator configured for driving the lead
screw to rotate which results in the transmission member together with
the lens group sliding along the longitudinal direction of the lead
screw;a slidable member secured to the lens group;a guide for guiding the
slidable member and the lens group when sliding along the optical axis,
the actuator, the slidable member, and the guide cooperating to keep the
transmission member and the lens group moving along the optical axis
without rotation about the lead screw; andtwo stop portions for
delimiting a movable boundary of the transmission member along the lead
screw, the transmission nut being disengaged from the lead screw, which
results in the lead screw stopping driving the transmission nut, in the
case that the surrounding portion abuts against one of the stop portions
and the lead screw continues rotating.

20. The lens module as claimed in the claim 19, wherein the transmission
nut is disengaged from the lead screw in the case of over rotating of the
lead screw.

Description:

[0004]Lens modules commonly employ a focusing/zooming function for
adjusting an image plane thereof to produce a high quality image. A
typical focusing/zooming lens module includes a lens barrel, a lens
group, a lead screw, a transmission nut, a motor, and two stop portions.
The lens group is slidably received in the lens barrel. The lead screw is
set so that the longitudinal direction thereof is parallel to the optical
axis of the lens group. The transmission nut is meshed with the lead
screw, and is connected to the lens group. The motor is configured for
driving the lead screw to rotate to force the transmission nut to move,
with the lens group, along the lead screw to a focused/zoomed position.
The two stop portions are configured for delimiting a movable boundary of
the transmission nut (the focusing/zooming range of the focusing/zooming
lens module).

[0005]In such focusing/zooming lens modules, an over-rotation of the lead
screw (the lead screw continues rotating until the transmission nut abuts
against the stop portion) caused by misoperations of users or control
errors of the motor may cause the lead screw to engage with the
transmission nut, and then cannot be disengaged. And so, the
focusing/zooming lens module loses the focusing/zooming function.

[0006]Therefore, it is desirable to provide a lens module with focusing
function, which can overcome the abovementioned problem.

SUMMARY

[0007]In a present embodiment, a lens module with focusing function
includes a lens group, a lead screw, a transmission member, an actuator,
and two stop portions. The lens group is slidable along the optical axis
thereof. The lead screw is set so that the longitudinal direction thereof
is parallel to the optical axis. The transmission member is secured to
the lens group, and includes a deformable screw-engaging portion. The
deformable screw-engaging portion is disengageably engaged with the lead
screw. The actuator is configured for driving the lead screw to rotate to
force the transmission member to move along the lead screw. The two stop
portions are configured for delimiting a movable boundary of the
transmission member along the lead screw. The deformable screw-engaging
portion disengages from the lead screw when the screw-engaging portion
abuts against the stop portion and the lead screw continues rotating.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]Many aspects of the present lens module should be better understood
with reference to the following drawings. The components in the drawings
are not necessarily drawn to scale, the emphasis instead being placed
upon clearly illustrating the principles of the present lens module.
Moreover, in the drawings, like reference numerals designate
corresponding parts throughout the several views.

[0009]FIG. 1 is a schematic, cross-sectional view of a lens module with
focusing function, according to a first embodiment;

[0010]FIG. 2 is an enlarged, sectional view of a portion II of FIG. 1;

[0011]FIG. 3 is a cross-sectional view taken along line III-III of FIG. 1;

[0012]FIG. 4 is a schematic, cross-sectional view of a lens module with
focusing function, according to a second embodiment; and

[0013]FIG. 5 is a cross-sectional view taken along line V-V of FIG. 4.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014]Embodiments of the present lens module will now be described in
detail with the references to the drawings.

[0015]Referring to FIG. 1, a lens module 100 with focusing function,
according to a first embodiment, includes a lens barrel 10, and a lens
group 20, a lead screw 30, a transmission member 40, an actuator 50, a
slidable member 60, a guide 70, and two stop portions 81, 82 all received
in the lens barrel 10. The lens group 20 is accommodated in the lens
barrel 10 so that the optical axis thereof is essentially parallel to the
longitudinal direction of the lens barrel 10. The lead screw 30 is set so
that that the longitudinal direction thereof is essentially parallel to
the optical axis. The transmission member 40 is secured to the lens group
20, and includes a deformable surrounding portion 41 partially
surrounding the lead screw 30. The surrounding portion 41 is engaged with
the lead screw 30. In other words, the surrounding portion 41 (or named
as "screw-engaging portion") is a transmission nut meshed with the lead
screw 30. The transmission nut defines a longitudinal gap therein (i.e.,
partially surrounding the lead screw 30) and is connected to the lens
group 20. The actuator 50, e.g., motor, is configured for driving the
lead screw 30 to rotate. The slidable member 60 is secured to the lens
group 20. The guide 70 is configured for guiding the slidable member 60
as it slides along the guiding direction thereof. In particular, the
guide 70 defines a guiding groove 71 with the guiding direction
essentially parallel to the optical axis, and the slidable member 60 is a
fin/arm fitting into the guiding groove 71 and is slidable along the
guiding groove 71. Thus, the lens group 20 is capable of irrotationally
sliding along the optical axis, and the transmission member 40 can be
forced to move along the lead screw 30 without rotation about the lead
screw 30. Opportunely, the guide 70 can be integrally formed with the
lens barrel 10, namely, the guiding groove 71 is directly defined in the
inner surface of the lens barrel 10. The two stop portions 81, 82 e.g.,
two nuts fixed to the lead screw 30, are configured for delimiting a
movable boundary of the transmission member 40 along the lead screw 30.
The surrounding portion 41 thus structured will disengage from the lead
screw 30 when it abuts against the stop portion 81/82, and the lead screw
30 continues rotating.

[0016]The lens group 20 includes a barrel-shaped holder 21 and a pickup
lens 22. The pickup lens 22 is held/received in the holder 21. The
transmission member 40 and the slidable member 60 are secured to the
holder 21. Understandably, the transmission member 40 and/or the slidable
member 60 can be integrally formed with the holder 21. In this
embodiment, the transmission member 40 is secured to the holder 21 using
adhesive, and the slidable member 60 is integrally formed with the holder
21. Alternatively, the lens group 20 could employ more pickup lenses,
aperture stop and/or other optical components concentrically held within
the holder 21 to assure a high quality of imaging thereof.

[0017]It should be understood that the lead screw 30 and the transmission
member 40 are configured for, cooperating together, (1) transmitting a
rotation motion of the actuator 50 into a linear motion of the lens group
20 to move the lens group 20 to a desirable focusing/zooming position;
and (2) enabling the lead screw 30 idling with respect to the surrounding
portion 41, in the case that misoperations or control error occur and
cause the lead screw 30 to over rotate, to avoid over-tight engagement
between the lead screw 30 and the surrounding portion 41. Therefore, high
power-transmission efficiency and disengageability between the
surrounding portion 41 and the lead screw 30 is desirable.

[0018]Referring to FIG. 2, in order to achieve the high power-transmission
efficiency, the lead screw 30 and the surrounding portion 41 are engaged
with each other using multiple threads, a large thread angle α of
the multiple threads is preferable (the larger the thread angle α
is, the higher power-transmission efficiency is), and a large radian
(>120°) of the surrounding portion 41 is preferable. On the
other hand, in order to get disengageability, the surrounding portion 41
is made of deformable material such as resilient plastic (e.g.,
polyoxymethylene) or resilient metal (e.g., elastic steel), and a small
thread α of the multiple threads is preferable (the smaller the
thread angle is, the smaller the engaging force of the multiple threads
is, and the surrounding portion 41 is more likely tend to disengage from
the lead screw 30 in the small thread angle α case). To balance
these two facors, the thread angle α is preferably in an
approximate range of 45°˜60°.

[0019]Also referring to FIG. 3, in this embodiment, the thread angle
α is about 55°, the surrounding portion 41 partially
surrounds the lead screw 30 on three sides, and is made of
polyoxymethylene, because polyoxymethylene has other advantages: adequate
stiffness (for carrying the lens group 20 moving along the lead screw
30), excellent self-lubricity (for decreasing rotation friction force
between the surrounding portion 41 and the lead screw 30), excellent
formability, and low cost.

[0020]The actuator 50 can be a servomotor or a step motor, and is
electrically connected to, and is controlled by a control circuit (not
shown). The lead screw 30 is coupled to, e.g., directly fixed to or gear
engaged with, a rotor of the actuator 50.

[0021]The surrounding portion 41 can be forced to disengage from the lead
screw 30 when the surrounding portion 41 abuts against the stop portion
81/82 and the lead screw 30 still rotates. Thus, tight engagement between
the surrounding portion/transmission nut 41 and the lead screw 30 is
avoided. Understandably, if tight engagement of the lead screw 30 is
prevented, the lead screw 30 can be driven to reversely rotate to force
the transmission member 40 to move, along with the lens group 20, in a
reverse direction. Namely, focusing/zooming function of the lens module
is protected from the ill effects of over rotation of the lead screw 30.

[0022]Referring to FIG. 4, a lens module 200 with focusing function,
according to a second embodiment, is essentially similar to the lens
module 100 except with respect to the surrounding portion 41a, the
slidable member 60a, the guide 70a, and the stop portions 81a, 82a.

[0023]Also referring to FIG. 5, the surrounding portion 41a almost, but
not quite, completely surrounds the lead screw 30 to provide a higher
meshing force for forcing the transmission member 40 to move.

[0024]The slidable member 60a defines a through hole 61a. The guide 70a is
a guiding rod. The guiding rod is set parallel to the optical axis, and
is matingly inserted through the through hole 61a, thus the slidable
member 60a is capable of sliding along the guiding rod.

[0025]The lens barrel 10 defines a concave space 11, the lead screw 30 is
rotatably received in the concave space 11. In this embodiment, two
surfaces bounding the concave space 11, facing each other and essentially
perpendicular to the lead screw 30, act as two stop portions 81a, 82a.

[0026]It will be understood that the above particular embodiments and
methods are shown and described by way of illustration only. The
principles and the features of the present invention may be employed in
various and numerous embodiment thereof without departing from the scope
of the invention as claimed. The above-described embodiments illustrate
the scope of the invention but do not restrict the scope of the
invention.

Patent applications by Bin Lei, Foshan CN

Patent applications by HON HAI PRECISION INDUSTRY CO., LTD.

Patent applications by PREMIER IMAGE TECHNOLOGY(CHINA) LTD.

Patent applications in class Electromagnetic or piezoelectric drive

Patent applications in all subclasses Electromagnetic or piezoelectric drive